Method and apparatus for producing a cable

ABSTRACT

In the method for manufacturing a cable (CA 1 ), the individual leads (AD 1  through ADn) are supplied to a stranding apparatus (RE, RA) that produces a stranded bundle (SB 1 ), whereby the material (MMA 1 ) for the cable cladding (MA 1 ) is applied onto the stranded bundle (SB 1 ) produced in this way with an extruder head (EK 1 ), and the stranding point for the stranding lies in the region of the extruder head (EK 1 ). The individual leads (AD 1  through ADn) are already brought into contact with the material (MMA 1 ) for the cable cladding (MA 1 ) when or before they have just been completely stranded to form the stranded bundle (SB 1 ).

BACKGROUND OF THE INVENTION

The invention is directed to a method for manufacturing a cable, wherebythe individual leads are supplied to a stranding means that generates astranded bundle, whereby the material for the cable cladding is appliedonto the stranded bundle manufactured in this way with an extruder head,and the stranding point for the stranding lies in the region of theextruder head.

DE-A1 35 09 404 discloses a method of this species. The material for thecable cladding is thereby only applied onto the completely strandedbundle, so that there is an intermediate region wherein the strandedbundle as a whole is guided in a cylindrical guide sleeve. On the onehand, this structure lengthens the axial expanse of the extruder headand is less advantageous for various applications due to the subsequentapplication of the cladding material onto the stranded bundle.

The invention is based on the object of disclosing a way how theapplication of the cladding material can be more beneficiallyimplemented. This object is achieved in a method of the speciesinitially cited in that the individual leads are already brought intocontact with the material for the cable cladding when or before theyhave been completely stranded to form the stranded bundle.

Since the individual leads are already brought into contact with thecladding material at the moment of their convergence or in the not yetcompletely stranded condition, this material can penetrate better intogrooves and gaps, at least in the outside layer, and fix the leads.Further, the connection between cladding material on the one hand andthe outside contour of the stranded bundle on the other hand is firmerin this way, so that the adhesion opposing a potential unraveling can beimproved. The structural length of the manufacturing line (composed ofstranding machine and cladding system) can generally also be reduced inthis way because the leads need not first be merged completely into thebundle and the application of the cladding material is then subsequentlyundertaken at a greater distance; rather the stranding is directlyintegrated into the cladding machine.

The invention is also directed to an apparatus for manufacturing a cablewith a stranding means to which individual leads are supplied forforming a stranded bundle, and whereby an extruder head is provided forapplication of a material for the cable cladding. This apparatus ischaracterized in that the individual leads are guided such in the insideof the extruder head that they come into contact with the material forthe cable cladding when or before they are completely stranded to formthe stranded bundle.

Developments of the invention are reflected in subclaims.

The invention and developments thereof are explained in greater detailbelow with reference to drawings. Shown are:

FIG. 1 a section through an extruder head with guidance of the leadsaccording to the invention;

FIG. 2 a perspective illustration of a stranding means for applicationin the invention;

FIG. 3 a further exemplary embodiment of the invention with an extruderhead shown in section; and

FIG. 4 a cross section through a cable manufactured according to theinvention.

FIG. 1 shows a section through an extruder head EK1 that comprises asleeve-shaped outside body EH in whose bore inserts ET11, ET12 and ER13are provided. Leads AD1-ADn enter from the right, these potentiallybeing optical and/or electrical conductors. Given employment of opticalconductors (light waveguides), these can be fashioned as solid or hollowleads, whereby the light waveguides—in the latter instance-are arrangedin the inside of a tubular protective sheath and this is advantageouslyfilled with a soft, pasty filling compound. Further, a tensile centralelement CE1 is provided onto which the leads AD1-ADn are stranded withthe same or-as indicated by the arrow PF1—with changing strandingdirection, so that a stranded bundle SB1 arises as the final result. Anoutside cladding MA1 is applied onto this stranded bundle SB1 in theextruder head EK1. The plastic material MA1 for this outside cladding ispressed into the extruder head EK1 in practically liquid form—by anextruder that is not shown here—and is thus applied onto the strandedbundle SB1.

The leads AD1-ADn as well as the central elements CE1 pass through boresthat are applied in the input-side, disk-shaped inserts ET13 and ET12.These bores, which proceed obliquely inward in the direction of thetraversal axis, are referenced OP11 through OP1n for the leads AD1through ADn. The practically liquid cladding material MA1 reaches theindividual leads AD1-ADn in a position wherein these are just beingmerged to form a stranded bundle and have not yet been completelycombined to form the finished stranded bundle SB1. Expressed in otherwords, the leads AD1-ADn do not yet lie completely tightly against thecentral element CE1 but still exhibit a certain distance therefrom or,respectively, from one another, preferably between 0.5 and 2 mm.

As a result thereof, the material MMA1 still adequately proceeds intothe gores between the individual leads AD1-ADn and largely fills these,as particularly follows from FIG. 4, which shows a cross section througha cable CA1 manufactured in this way. It can be seen therein that, inany case, the outer gores AZ are completely and deeply filled as aresult of this way of delivering the cladding material and, thus, thestranded union is secured against unraveling, even given SZ-stranding.The leads AD1-ADn are indicated here as hollow leads in whose insidelight waveguides LW1 through LWm are arranged, potentially embedded in afilling compound, preferably with excess length. The central coreelement CE1 is composed of a tensile core CK1 (for example, of steelwires or GFK elements), whereby a coating CB1, particularly of plasticmaterial, can be potentially applied on the outside for achieving thenecessary diameter values.

There are various possibilities of filling for the inside gore IZ, i.e.the gore between the central element CE1 and the individual leadsAD1-ADn, in order to achieve longitudinal water tightness. First, it ispossible to already pre-coat the central elements CE1 with a fillingcompound serving the purpose of achieving the necessary longitudinaltightness before the stranding of the individual leads AD1-ADn and tostrand the leads AD1-ADn only thereafter. However, it is also possibleto apply a band, fabricate or the like on the central element CE1 thatis coated with a material that swells given the admission of water.

Since the material MMA1 for the cladding MA1 is supplied in soft formbefore or precisely at the convergence of the leads AD1-ADn in theultimate stranded union, one can also proceed such that the materialalso proceeds toward the inside, i.e. up to the central element CE1, andthus also fills the inside gores IZ. This is particularly true whenextremely liquid cladding material and/or high pressure are used. It isthus not usually necessary to provide an additionally filling compoundfor the inner gores IZ. The cladding material MMA1 advantageouslyencounters the various leads AD1-ADn in an annular gap arranged in theextruder head (see FIGS. 1 and 3), whereby the leads AD1-ADn are stillseparated laterally from one another by spacings in this condition, i.e.do not lie directly against one another. The material MMA1 can thusenter between the leads AD1-ADn in a simple way, and can thus also atleast partially but preferably completely fill the inner gores IZaccording to FIG. 4. When, in contrast, the cladding material MMA1encounters the leads AD1-ADn when they are just touching one another,then only the outer gores AZ are essentially closed. All the morematerial proceeds into the inside and, preferably, to the centralelement CE1 as well the farther the leads AD1-ADn are distanced from oneanother when the admission of the material MMA1 ensues.

FIG. 2 shows a stranding apparatus with which a cable CA1 of FIG. 1 orFIG. 4 can be manufactured. Supply reels VS1-VSn on which leads AD1through ADn are contained are provided on two haul-off racks AG1 andAG2. A supply drum CT is also present from which the central element CE1is hauled off. It is assumed in the present example that theSZ-stranding is undertaken with the assistance of this central elementCE1. To this end, this central element CE1 is conducted over a drum RE(with at least one wrap) whose rotational axis proceeds transverselyrelative to the traversal direction of the central element CE1 throughthe stranding apparatus. The drum RE is held in a bearing block RB that,together with the drum RE, is held rotatable around an axis at its endsides via bearings LG1 and LG2, this axis proceeding through thestranding apparatus parallel to the traversal direction of the centralelement CE1. Adequate space is to be provided for the rotation of thebearing block RB around the axis parallel to the traversal direction ofthe central element CE1, whereby this space is mainly dependent on thedrum diameter of the drum RE. In reality, the haul-off racks AG1 and AG2are arranged at a greater distance from one another than shown. Therotational sense of the bearing block RB is modified, preferablyperiodically, as indicated by the arrow PF2. The central element CE1 isthus twisted in alternation in the one direction and then back in theopposite direction, and is thus supplied to an extruder head EK1 whosesectional view is shown in FIG. 1. The appertaining extruder isreferenced EX. Further, the leads AD1-ADn enter into the extruder headEK via corresponding openings in an input or guidance ring.

After passing through the extruder head EK, the cladding material, whichis still hot and soft, is supplied to a cooling means KE (preferably,water cooling; advantageously, in counter-flow principle) and thenproceeds to a caterpullar RA in the present example. This caterpullar RAserves, first, for pulling the individual leads AD1-ADn as well as thecentral element CE1 off and moving them forward, for which reason thebelts the caterpullar RA enclose the cable CA1 and thus convey itforward from right to left. The caterpullar is additionally rotatablyseated at one side via respective bearings LG3 and LG4. In addition to adrive for the two conveyor belts of the caterpullar RA, a further drive(not shown here) is to be provided that places the caterpullar RA inrotation around a respective axis proceeding parallel to thelongitudinal axis of the cable CA1 in conformity with the arrow PF3,whereby the rotational sense is modified, preferably periodically. Thecircumferential speed and the rotational sense are respectively selectedthe same for the caterpullar RA and for the drum RE, so that the two areoperated synchronized with one another, particularly by utilization of acommon control means CU for both. It is also possible, as indicated withbroken lines, to likewise have the extruder head EK1 co-rotatesynchronized therewith. The caterpullar RA represents not only a meansfor moving the cable CA1 as well as the elements contained in itforward, but simultaneously acts as a stranding means together with thedrum (twister) RE rotating at the input side. The two elements RE and RAserving for stranding enclose the extruder head EK1, as a result whereofthe penetration events for the cladding material explained in greaterdetail in conjunction with FIG. 1 is assured. The finished cable CA1 iswound onto a take-up drum AT.

Instead of the illustrated stranding elements, for example the twisterRE and the caterpullar RA, other known stranding means utilized in theframework of SZ-stranding can be employed. For example, a rotatingcaterpullar analogous to RA can be employed as well instead of the disktwister RE. Conversely, it is also possible to employ a rotating twisterat the output instead of the caterpullar RA.

The extrusion nozzle of the extruder head EK can co-rotate synchronizedwith the stranding disk or, respectively, stranding crawler. Given astationary extrusion nozzle, the stranding preferably occurs betweenextrusion nozzle and cooling trough where the cladding material is stillplastic. It is also possible to conduct the leads to be stranded intothe injection head without rotation and to apply the rotation requiredfor the stranding (wrong lay or SZ) following the injection head. Theoutside cladding then rotates together with the stranding lay.

Instead of SZ-stranding, a long lay stranding can also be implementedwith the stranding apparatus shown in FIG. 2 when the elements RE and RArotate in only one direction, and when the take-up drum AT as well asthe haul-off of the central element CE1 are also rotated.

FIG. 3 shows a section through an extruder head EK2 to which strandingelements AD1 through ADn are supplied. In contrast to FIG. 1, no centralelement is provided here, i.e. only individual leads AD1-ADn arestranded or, respectively, bunched with one another, namely likewiseadvantageously in different stranding directions, as indicated by thearrow PF4. The material MMA2 for the cladding MA2 of the cable CA2 to beproduced likewise already encounters leads AD1 through ADn here at apoint where these are still at an adequate distance from one another.This means that the entire inside of the stranded bundle SB2 iscompletely filled with the cladding material MMA2 without difficulty.For an extruder head according to FIG. 3, a tube store can alsopreferably be employed as stranding apparatus, this being arrangedimmediately before the admission into a rotating perforated or guideplate ET21 that serves for the introduction and forwarding of the leadsAD1-ADn and which, accordingly, comprises bores arranged n-annularly. Inthe latter instance, the core is already stranded before the claddingmaterial encounters the core. The cladding material in this casefunctions as rotation block.

What is claimed is:
 1. A method for manufacturing a cable comprising thesteps of providing a stranding apparatus which generates a strandedbundle comprised of a plurality of leads and has a stranding point,providing an extruder head for applying a cladding material for thestranded bundle adjacent the stranding point to thereby form a cablecladding surrounding the plurality of leads, supplying individual leadsto the stranding apparatus, contacting the individual leads with thecladding material from the extruder head by the time that the leads arebrought into the stranding point so that the leads are provided with thecladding material prior to being completely stranded to form thestranded bundle, and completing the stranding of the bundle with thestranding apparatus after the bundle has passed through the extruderhead.
 2. A method according to claim 1, which includes providing acentral tensile element and stranding the leads thereon.
 3. A methodaccording to claim 2, wherein the step of providing a central tensileelement provides an element coated with a soft filler material before itis introduced into the extruder head.
 4. A method according to claim 1,wherein the cladding material is introduced onto the elements so thatthe cladding material fills the outside gores of the stranded bundle. 5.A method according to claim 1, wherein the cladding material isintroduced on the individual leads before the leads are brought togetherso that the cladding material fills the inside gores of the strandedbundle.
 6. A method according to claim 1, which further includes passingthe stranded bundle with the cladding through a cooling means after itpasses through the extruder head, and then advancing the stranded bundleto at least a portion of the stranding apparatus.
 7. A method accordingto claim 1, which includes changing the stranding direction to producean SZ-stranding.
 8. An apparatus for manufacturing a cable with astranding means in which individual leads are supplied to form astranded bundle, said apparatus including an extruder head beingprovided for application of a cladding material on the bundle to-therebyform a cable cladding surrounding the plurality of leads with theimprovement being the individual leads being guided in the inside of theextruder head as they come into contact with the cladding material priorto being completely stranded to form the stranded bundle, and at least aportion of the stranding means being arranged following said extruderhead.
 9. An apparatus according to claim 8, wherein the strandingapparatus includes means for changing the direction of stranding toproduce an SZ-stranding.